BtVS: Go Fish / Cordy's costumes

Earlier in the season Xander makes a snarky comment saying that Cordelia should "wear something trashy-er" which implies that Cordy's costume of choice is trashy - I'll offer one episode of evidence to reject that and expose it as lazy writing...

Clearly there is, however, evidence that Cordy has too many clothes if she gets through six costumes in an episode...